The message “No SIM card” or the disappearance of the network icon on the Samsung Galaxy screen instantly blocks calls and mobile data, turning a functional smartphone into a useless device. This error occurs both on budget models and on the latest flagships of the S23 and S24 series, forcing owners to look for an urgent solution to the problem with SIM card recognition in the Android settings or the hardware of the gadget.
The reasons for the failure can be the most trivial: from simple contact contamination to a serious software conflict in the firmware Android or hardware failure slot. Before taking the device to a service center, it is worth trying a number of independent actions, which in 80% of cases restore communication. We will analyze the complete algorithm for diagnosing and troubleshooting, starting with simple steps and moving on to complex settings.
Primary diagnosis and physical check of the tray
The very first step that needs to be performed is a basic check of physical contact. Often the problem lies not in the phone itself, but in how the card is installed. Remove the tray using a special paper clip and carefully inspect the chip. There should be no oxides, grease or dust on the golden contacts. Even microscopic contamination can disrupt the connection between reader and the card.
If the contacts appear dirty, gently wipe them with a soft, lint-free cloth lightly moistened with alcohol. Do not use harsh chemicals or water. Also check the tray itself: it should fit tightly into the body until it clicks. If the tray dangles or fits crookedly, the contact with the motherboard will be unstable and the phone will lose the network.
Pay attention to the card format. Modern smartphones Samsung use nano-SIM. If you are using an older card that was cut by hand with scissors, there is a high risk of chip damage or thickness mismatch. In such cases reader may simply not reach the contacts.
⚠️ Attention: Never insert the tray back if the SIM card is displaced and does not lie flat in the recess. This may lead to jamming of the mechanism or damage to the pins inside the slot.
Try installing the SIM card in another slot if your smartphone supports two cards. Sometimes one of the slots fails due to frequent use or moisture, while the second continues to work properly. This will help localize the problem: the slot or the card itself is faulty.
☑️ Quick check of the tray
Soft reset and reboot of the radio module
Sometimes the operating system Android simply “freezes” in a state where the radio module drivers cannot initialize the connection correctly. In this case, a soft reboot of network interfaces without completely turning off the phone helps. This action is safe and does not delete your personal data, photos or applications.
To perform a network soft reset, go to the settings menu. Find the section Connections or General settings, then select Reset network settings. Confirm the action by clicking the appropriate button. After this, the phone will reboot the communication modules, and you will need to re-enter passwords for Wi-Fi networks, but the Bluetooth and mobile data settings will return to factory settings.
An alternative method is to use the engineering menu to check the status IMEI. Enter the code *#06#in the dialer. If the screen displays IMEI numbers for both slots, it means that the radio module is working and sees the hardware. If instead of numbers you see dashes or an inscription Nullthe problem is deeper and concerns the firmware or hardware.
What to do if the IMEI is not displayed?
If after entering the code *#06# the number is not shown, try updating the firmware through the Odin app on your computer. In rare cases, it is necessary to reflash the modem, which is best left to specialists.
It would not be superfluous to check whether it was accidentally activated airplane mode. Although this seems obvious, sometimes the system may become visually stuck in this mode even if the airplane icon is not lit. Turn airplane mode on and off through the notification shade three times in a row at 5-second intervals. This will force a restart of the search for cell towers.
Before resetting the network settings, make sure that you remember the passwords for important Wi-Fi networks, as they will be deleted during the process of restoring the connection to factory settings.
Checking the SIM card for compatibility and serviceability
Not all SIM cards are equally useful for modern smartphones. If your card was issued more than 5-7 years ago, its chip may be physically worn out or may not support modern encryption protocols required by telecom operators. Older cards often have a thicker layer of plastic around the chip, which prevents them from sealing tightly in the nano-SIM slot.
The best diagnostic method is the method of exclusion. Insert your SIM card into another phone. If it is not detected there either, it means the card is faulty. In this case, you need to contact your operator's service center for a free replacement while keeping the number. Usually this procedure takes no more than 15 minutes if you have a passport.
It is also worth taking into account regional characteristics. Some phones imported from other countries (so-called “gray” devices) may be locked to a specific operator or may not support Russian network frequencies in a certain range. Check the specifications of your model Samsung Galaxy on the official website to make sure it supports the ranges LTE Band 3, 7, 20that are most common in the Russian Federation.
| Symptom | Possible cause | Solution |
|---|---|---|
| Writes “No network” | Registration on the network failed | Select an operator manually |
| Constantly asks for a PIN code | Card blocking | Enter PUK code or replace card |
| See the card, but no Internet | Invalid APN access points | Reset APN settings |
| Detects only one of the two cards | The second slot is faulty | Check the tray or take it to service |
If the operator replaced the card and the problem remained, it may be a conflict between the phone software and the new communication profile. In rare cases, completely deleting operator profiles from the phone's memory before re-installing a new card helps.
Configuring access points and network settings
Often the phone sees the SIM card, but cannot connect to the Internet or make calls due to incorrect access point settings APN. These parameters are responsible for routing traffic in the operator’s network. If there are failures in updating the firmware or changing the operator, the settings may be lost or become irrelevant.
To fix this, follow the path Settings → Connections → Mobile networks → Access Points (APN). In the upper corner of the screen, click on the menu (three dots) and select Reset to default settings. After this, reboot your device. The phone will automatically load the correct settings for your carrier.
Also check the network mode. Go to Mobile networks → Network mode. Make sure that mode 5G/4G/3G/2G (auto-connect)is selected. If your phone stubbornly tries to connect to 5G only and the coverage in your area is weak, it may lose registration with the network. Switching to 3G/2G may temporarily restore connection for making calls.
⚠️ Attention: APN parameters may vary from different operators (MTS, Beeline, Megafon, Tele2). Do not create access points manually if you are not sure of the exact values - use the automatic reset function.
In some cases, disabling the function VoLTE (Voice over LTE) helps. This technology allows you to make calls over a 4G network, but it is unstable on some devices or with some operators. Try disabling the switch Calls via LTE in the mobile network settings and check if the operator icon appears.
Updating software and resetting to factory settings
If physical manipulations and network settings did not help, the reason may lie in an operating system error. Company Samsung regularly releases security patches and One UI updates that fix radio module bugs. Check for updates in the section Settings → Software update → Download and installation.
Make sure that the phone is connected to a stable Wi-Fi and is charged at least 50%. The update process may take from 10 to 40 minutes. After installing the new firmware version, the phone will automatically reboot and the communication drivers will be reinitialized.
The extreme measure of a software solution is a full reset to factory settings (Hard Reset). This action will delete all data from the internal drive, so be sure to back up your contacts, photos and documents to the cloud or to your computer. To reset, go to Settings → General settings → Reset → Data reset.
A full reset eliminates 90% of software conflicts, but requires first saving all important user data.
After the reset, the phone will start as new. Do not restore all applications from a backup at once. First, check the operation of the SIM card on a “clean” system. If the connection appears, it means that the problem was caused by some third-party application or a settings conflict.
Settings → General settings → Reset → Reset data → Reset phone settingsHardware faults and slot repair
When all software methods are exhausted, and the SIM card is working and works in other phones, we can only suspect a hardware failure. In smartphones Samsung Galaxy the SIM card slot is connected to the motherboard via a connector. Over time, from frequent removal of the tray, this connector may become loose, oxidize, or move away from the board.
Another common reason is moisture. Even if the phone has standard protection IP68, over time the tightness of the adhesive gaskets is broken. Microdroplets of water that get into the slot cause corrosion of the contacts. Visually, this may look like a dark coating on the contacts inside the hole for the tray.
In difficult cases, it may fail on its own radio module or the power circuit on the motherboard. This often happens after the device has been dropped or low-quality chargers have been used, causing voltage surges. Diagnosis of such a malfunction is possible only in a service center using a multimeter and an oscilloscope.
⚠️ Attention: Self-disassembly of a Samsung Galaxy smartphone will void the official warranty. If the device is under warranty, immediately contact an authorized service center.
Slot repair usually does not require replacing the entire motherboard. Craftsmen can resolder the connector or restore the tracks. The cost of this procedure is significantly lower than replacing the phone. However, if the problem is in the power controller, repairs may not be economically feasible for older models.
Is it possible to repair the slot yourself?
Without experience in soldering microcircuits and having a hair dryer, you cannot try to repair the slot. You risk damaging the cables and the screen when disassembling the case.
Frequently asked questions (FAQ)
Why does the phone see the SIM card, but says “Emergency calls only”?
This means that there is physical contact, but the phone cannot register in the operator’s network. Check to see if the card is blocked for non-payment, if airplane mode is turned on, and if the operator is manually selected in the network settings.
Can a case interfere with the operation of the SIM card?
Yes, some thick or incorrectly installed cases can put pressure on the SIM card tray, preventing it from going in all the way. Try removing the case and checking the phone's operation without it.
What to do if the phone asks for a PUK code?
A PUK code is needed if you entered the PIN code incorrectly three times. It cannot be picked up. Find the envelope that contained the SIM card, or find out the code in your operator’s personal account or support service.
Does Root access affect the operation of the SIM card?
Yes, obtaining superuser rights (Root) and installing custom firmware can disrupt the operation of the radio module, especially if the EFS section where IMEI is stored has been damaged. In this case, only flashing the stock software with EFS restoration will help.
Why did the network disappear after updating Android?
The update could reset the network settings or lead to a base frequency conflict. Perform a network reset or a full reset to factory settings to eliminate the software conflict.